Abstract: Here, we experimentally addressed the welding/brazing of Al-Li alloy 2195 and Ti-alloy TC4 with an electron beam in vacuum. The impact of the welding/brazing conditions on the microstructures, phase-structures and mechanical properties of the joint was investigated with scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and mechanical probes. The preliminary results show that an electron beam is capable of welding/brazing Al-Li alloy 2195 and Ti-alloy TC4 without oxidation under the optimized conditions. For example, no obvious pores and cracks were observed in the compact joint, comprising a 5 μm thick transition layer, close to Ti-alloy, and TiAl₃ dominated intermetallic compounds in the form of columnar, cellular and pyramid grains grown in transversal orientation to Al-Li alloy side. An average tensile strength of the joint was measured to be 260 MPa; and cleavage fracture might possibly occur in the fairly weak mid-join.